The present invention relates to bicycle shifters, and more particularly, to a bicycle shifter including a spring element that functions as a preload spring for cable-release operations and a detent pawl.
Typically, a rider selects a desired bicycle gear by actuating a shifter that pulls or releases a tensioned control cable connected to a gear change device such as a derailleur or an internal gear hub. Once a gear is selected, the bicycle shifter maintains the current selected gear. Shifters of this type are disclosed in German patents DE 103 58 438 and DE 100 43 612 A1.
These shifters generally include an actuator, a cable spool and a retaining device for maintaining the selected gear. The actuator rotates the cable spool and the retaining device prevents the cable spool from unwinding under the force of the tensioned control cable.
DE 103 58 438 A1 discloses a twist-shifter that generally includes a housing, a cable spool and an actuator in the form of a rotatable grip. The shifter further includes a detent pawl and a discrete preloaded spring. The detent pawl is supported by the housing and engages separate locking and releasing contours. The preloaded spring is arranged between the actuator and the cable spool to assist the cable-release operation.
DE 100 43 612 A1 also discloses a shifter that generally includes a housing, a cable spool, and a rotatable grip. The shifter further includes a pawl and a preloaded spring. The pawl is disposed on the cable spool and engages a plurality of teeth in the shifter housing. The preloaded spring, shown integral with the spool, assists in the cable-release operation. Alternatively, the pawl, preloaded spring and the cable spool may be configured as a single piece.
These shifters generally function in the same manner. During a cable-pull operation, the actuator is rotated in a first direction to wind the control cable as the detent pawl ratchets over the detent contour. Once the desired gear is selected, the detent pawl engages one of the teeth of the contour to maintain the current gear position. During a cable-release operation, the actuator is rotated in a second direction, opposite the first, to unwind the control cable. Upon initial rotation of the actuator, the spring is preloaded. Upon further rotation, the detent pawl is released from a current detent position by a release element. As the detent pawl displaces toward the next detent position, the spool is rotated, or accelerated, by the preloaded spring to boost or assist the cable unwind operation in addition to the tensile loading of the control cable.